[Tomcomm]

ED............When I first got the 21CT55 activated over a year ago, I had no way of setting the Ultor HV without a HV probe on my VTVM. I assumed the RCA engineers designed the HV portion of the CTC2B chassis to limit the HV control range to max spec for the 21AXP22 crt, somewhat above the 25KV recommended in the service manuals.Typical of my approach to design, I went for the max and left it there. Since I converted to the 21FBP22 in "64, rated at 27.5K to increase brightness, I saw no reason not to continue operating at max HV. The focus was in range and I got good convergence. Hey, it made great pictures didn't it?

Only last week when I hobbled-up a 100 to 1 HV probe and carefully calibrated it was I horrified to read 34KV Ultor or 6.5KV above RCA max spec! I immediately reduced the HV to 25KV and the screen looked terrible. I got it refocused but the convergence was way off. I then set HV to 28KV and the picture was somewhat better but convergence was still bad. Rather than getting into re convergence I simply returned HV to 34KV and posted this thread to get some expert advice. Maybe my junky HV probe is way off, but until I get a reading from a known commercial HV voltmeter I'm not going to go off screaming and mess up something that's working exceptionally well for over a year...Tom